Can someone help me find where CoreData is storing the SQL file it creates in iOS applications?
So far I've tried "Show package contents" on the .xcdatamodel file and also the .xcodeproj file...No dice!
Is there an editor for looking at the contents of these SQL files?
Cheers.
-A
The url parameter of [NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:url:options:error] specifies the location of the file. Find this call in your code and see where you've stored it. XCode templates will put it into the top of your application documents directory, but you can put it anywhere you like.
Note that Apple considers the contents of this database to be opaque and non-user-modifiable. Playing with the data in your store is likely to cause issues with Core Data.
It's typically saved into your application's documents directory, with the name of your data model.
So, for example, if my data model is called AppData.xcdatamodeld, it will be AppData.sqlite inside my app's document directory. You shouldn't really need to touch the .sqlite file though.
Hope that helps!
Core Data editor --> http://christian-kienle.de/CoreDataEditor/
Related
do we have any command line from where i can query the sqlite database, which is created by coding, and stored in the application's default Documents folder?
Turn on file sharing for the app, copy the database file to your Mac, and use the command line tools (sqlite3) that are there.
(Note to the previous editor: I appreciate editing of answers for accuracy, format improvements, and fixing typos...but, if you want to provide completely different information, I suggest providing your own answer instead of changing the meaning of another user's response.)
This is what is my understanding: the resources in the project folder are read only. So, almost all examples show copying a plist from the resources to the app's document folder. Why can we not simply find the app's document folder (after first run) and create the initial plist there (i.e. in the documents folder of the app so that subsequently we can modify the plist via code?
The answer is: Yes, you can create an initial plist there. But before you do this, consider using NSUserDefaults to save the settings.
Because there might already be data needed in a plist when the app is first installed; and that data has to come from somewhere. Why not from a plist?
I would also suggest using the Library folder rather than the Documents folder, just in case you do file sharing via iTunes at some stage. The Documents folder is available to the end user, whereas the Library folder is not.
I would like to know if it is possible to create the file of a database by programming?
Actually I need to create a database if it does not exist.
I'll assume you have your own valid reasons for using sqlite3 directly rather than Core Data. There are certainly cases where it's appropriate.
The sqlite_3_open() function will create the database if it doesn't already exist. The sqlite3_open_v2() function will create the database if you pass SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE in the flags parameter. See the documentation for more details.
Of course on iPhone you'll need to make sure you're creating the database in a read-write directory such as the app's Documents directory, as opposed to the Resources directory, which is read-only.
In practice I've never tried building a database from the ground up on the iPhone. I always found it simpler to just include an empty DB file with the schema pre-built as an application resource, and then copy the file to the Documents directory the first time the app is run.
Are you sure that you need to create the database file directly? Maybe you should check out the Core Data Framework.
Thanks for your answers, I have never used Core Data so I will have a look on this.
For the moment I also copy a DB file from the Resource directory to the Documents but I would like to create a static library which can be used by many persons. So I would give a minimum of files to add to their project. That's the reason.
i am working on an application that displays read-only data i am shipping.
it is more of a book.
It is easy with SQLite but i am not satisfied with the performance and trying to use Core Data.
The issue is with pre-filling Core Data is that it is a hard process.
My question is:
Is it possible to build an assistant iphone application (for me to use) which uses the same data model for pre-filling.
and then take the populated .xcdatamodel file and use it in my original application?
I hope this makes sense :)
Adham
I believe what you're asking is whether you can create a CoreData database upfront and copy it to the iPhone. Is that correct?
This article will help. Here's a quote:
I thus suggest the following five-step process:
Create your data in a comma-separated file, typically placing each row of data (an entity) in a row of the file and separating different columns (its attributes) by commas.
Write a standalone program and copy in your .xcdatamodel file from your main project.
Write code in your new program that parses your comma-separated file and inserts the information into a Core Data persistent store that should be identical to the persistent store in your main project.
Run the program in the Simulator
Copy your data from the Simulator's documents directory into your actual project's bundle.
It's possible, I've done it. I made a desktop application to read from a CSV file using the code here:
http://www.mac-developer-network.com/columns/coredata/may2009/
I just had to alter the way the CSV part worked, and change the model.
I copied and pasted my model from the model builder into the iPhone model. (Clicked on the "grid" area, selected all, copied)
Then I took the sqlite database the desktop app produced (found it in Application Support, in the folder for this application) and put it into the resources folder
I made some code to copy the sqlite into the documents folder on the iPhone (if it wasn't already there) at startup, in the applicationDidLaunch method. It's possible that having it in the resources folder is no good. Even though you're using the database as read only, Core Data may want to write something to it. Not sure about this though..
I used the sqlite file in the documents folder in my Core Data set up.
The desktop and iPhone Core Data sqlite file seem to be exactly the same format. You can transfer one sqlite file to another application (iPhone to iPhone too) as long as they have the same data model. In another application, I used NSXMLParser to create the Core Data sqlite file, then transferred it to another app, both on iPhone using the Simulator.
Yeah, your data source can be whatever you want it to be. The other suggestions are good ones. Create a managed object model (.xcdatamodel) identical to what you want to use in your app. Read in the data from your file, create a new instance of your managed object and populate it from the file. Then save, and dive into the bundle in the iPhone Simulator and copy it over. This has the added bonus of being in exactly the format you need, with all the helpful metadata. Copy your object model and your managed object classes and you're good to go.
Note, though, if you really intend for it to be read-only, and you're using it at install, it will be installed in your finished app's bundle (under Applications/{SIGNATURE}/Myapp.app). If you intend to edit this database or allow a user to save to it, it's a better idea to copy it to the Applications/{SIGNATURE}/Documents directory where your user database lives.
I'm trying create 2 apps, one that builds a persistent store, and another one that consumes it.
So far I have built one app that uses CoreData to successfully build a database from an XML file. So this project contains the data model, the .h/.m files for the entities, etc.
I'm now trying to enable the second app to read that .sqlite file by copying the data model file, the .h/.m files related to the entities and the sqlite file to that project (via add existing).
The code executes but always fails to find any objects in the database.
Are there any restrictions or correct steps to take when trying to copy over these files?
The solution here is deceptively simple.
Just copy your .xcdatamodel file from one project to another and then when you run your app in the simulator for the first time it'll create a Documents folder for the app. Just drop your saved .sqlite or .binary files into the yourApp/Documents directory on the device.
You can find the simulator directory in "~user/Library/Application Support/iPhone Simulator".
You can also download, edit, and upload the myApp directory on a provisioned iPhone by dragging and dropping into and out of the Organizer. Look at the Applications list.
The iPhone doesn't support xml stores with core data, only sqlite or atomic (binary). The sqlite store is by far the better option for most applications since it doesn't all have to be loaded into memory at runtime.
Is this what you meant?
I think (not 100 percent sure) in your app plist, if you set your application bundle name to the same thing, they will share resources because the device will think they are the same application...
I don't think this is going to work the way that you want it to. On the iPhone, each application runs in its own "sandbox", and it's not really possible for one application to write files that another can read.
Is it really two different projects, or is it two targets in the same project? That would seem to make a lot more sense, and then you can share entity objects as they change.
For copying core data files from one project to another, I first created a new project with core data support and then I opened the contents of the previous coredata file and except the root tag, pasted all child tags in the new core data file in new project.
Previousy I tried to delete the coredata file in new project, copy pasted the previous one and changed its name and it was not working.